YAC-Bus : an interface for microprocessor-controlled peripherals

The use of the microprocessor to control a computer's peripheral changes the criteria for the interface between the peripheral and computer. An interface is described in which the data handled by the peripheral is stored in the microprocessor's own memory and the minicomputer is provided with the means to access this data through its IO system. The interface allows up to 16 microprocessor-controlled peripherals to be interfaced in a manner that places few requirements on the capabilities of a minicomputer's IO system, a feature which permits portability between various types of minicomputer. Details of implementation for a PDP-11 minicomputer and a 6800 microprocessor are given. Finally, the weaknesses of the implementation are examined and a comparison between the interface and conventional direct memory access methods is made